chromedp-gen

About chromedp-gen

chromedp-gen is a standalone cli tool for the chromedp package that generates the types for the chrome domain APIs as defined in Chrome's protocol.json.

Updating protocol.json

Run update.sh to retrieve and combine the latest browser_protocol.json and js_protocol.json from the Chromium source tree into protocol.json.

Installing quicktemplate and easyjson

chromedp-gen uses quicktemplate for code generation templates, and uses easyjson for JSON marshaling/unmarshaling.

Unfortunately, both of these projects cannot be used directly out of the box, as the versions used by chromedp-gen make use of a couple minor modifications:

1. quicktemplate has been modified to recognize '{% end %}' templates
2. easyjson has been modified to always output generated code in the same order (previously, the mailru version did not always generate the same output, as a couple points in the code were being affected by the Go map/key order issue).

I (kenshaw) have put in issues/pull requests to both projects in the hope that the changes I've made get merged and/or fixed otherwise.

For now, the exact versions that are in use with chromedp-gen can be obtained on my personal Github account:

• github.com/kenshaw/quicktemplate
• github.com/kenshaw/easyjson

The commands (and their associated dependencies) can be installed in the usual Go way:

go get -u github.com/kenshaw/quicktemplate/qtc github.com/kenshaw/easyjson/easyjson

Each package provides a command (qtc and easyjson, respectively) that need to be available on the path for the chromedp-gen command to work.

Generating types for chromedp

Assuming the qtc and easyjson commands are available (see above), one can then run the build.sh which will handle generating template files, and building/invoking the chromedp-gen command.

Reference Output

The output of running update.sh and build.sh is below:

ken@ken-desktop:~/src/go/src/github.com/knq/chromedp/cmd/chromedp-gen$ ./update.sh
# download
curl -s $BROWSER_PROTO | base64 -d > $BROWSER_TMP
curl -s $JS_PROTO | base64 -d > $JS_TMP

# merge browser_protocol.json and js_protocol.json
jq -s '[.[] | to_entries] | flatten | reduce .[] as $dot ({}; .[$dot.key] += $dot.value)' $BROWSER_TMP $JS_TMP > $OUT

# convert boolean values listed as strings to real booleans
# (this is not used in favor of using the custom Bool type that correctly JSON unmarshals the value)
# left here for completeness
#perl -pi -e 's/"\s*:\s*"(true|false)"/": \1/g' $OUT
ken@ken-desktop:~/src/go/src/github.com/knq/chromedp/cmd/chromedp-gen$ ./build.sh
go generate
qtc: 2017/01/29 09:10:16 Compiling *.qtpl template files in directory "templates"
qtc: 2017/01/29 09:10:16 Compiling "templates/domain.qtpl" to "templates/domain.qtpl.go"...
qtc: 2017/01/29 09:10:16 Compiling "templates/extra.qtpl" to "templates/extra.qtpl.go"...
qtc: 2017/01/29 09:10:16 Compiling "templates/file.qtpl" to "templates/file.qtpl.go"...
qtc: 2017/01/29 09:10:16 Compiling "templates/type.qtpl" to "templates/type.qtpl.go"...
qtc: 2017/01/29 09:10:16 Total files compiled: 4

go build

time ./chromedp-gen
2017/01/29 09:10:17 skipping command Page.getCookies [redirect:Network]
2017/01/29 09:10:17 skipping command Page.deleteCookie [redirect:Network]
2017/01/29 09:10:17 skipping command Page.setDeviceMetricsOverride [redirect:Emulation]
2017/01/29 09:10:17 skipping command Page.clearDeviceMetricsOverride [redirect:Emulation]
2017/01/29 09:10:17 skipping command Page.setGeolocationOverride [redirect:Emulation]
2017/01/29 09:10:17 skipping command Page.clearGeolocationOverride [redirect:Emulation]
2017/01/29 09:10:17 skipping command Page.setDeviceOrientationOverride [redirect:DeviceOrientation]
2017/01/29 09:10:17 skipping command Page.clearDeviceOrientationOverride [redirect:DeviceOrientation]
2017/01/29 09:10:17 skipping command Page.setTouchEmulationEnabled [redirect:Emulation]
2017/01/29 09:10:17 skipping command param Emulation.setDeviceMetricsOverride.offsetX [deprecated]
2017/01/29 09:10:17 skipping command param Emulation.setDeviceMetricsOverride.offsetY [deprecated]
2017/01/29 09:10:17 skipping command param Tracing.start.categories [deprecated]
2017/01/29 09:10:17 skipping command param Tracing.start.options [deprecated]
2017/01/29 09:10:17 skipping domain Console (console) [deprecated]
2017/01/29 09:10:17 running goimports
2017/01/29 09:10:31 running easyjson (stubs)
2017/01/29 09:10:31 running easyjson
2017/01/29 09:10:39 done.

real	0m22.318s
user	1m15.132s
sys	0m53.592s

go install ../../cdp/...
ken@ken-desktop:~/src/go/src/github.com/knq/chromedp/cmd/chromedp-gen$